One New Quinazoline‐Containing Diketopiperazine Isolated from the Marine‐Sponge‐Derived Fungus Penicillium sp. SCSIO41043

One new quinazoline-containing diketopiperazine (1), along with 24 known compounds including nine alkaloids (2-9, and 25), thirteen lactones (10-22), aspterric acid (23), and catechol (24), were isolated from the marine sponge-derived Penicillium sp. SCSIO41043. Their planar structures were unequivocally elucidated by spectroscopic analysis. The absolute configuration of 1 was determined by a comparison of reported and experimental electronic circular dichroism (ECD) spectra. Compound 16 was found to notably inhibit the growth of five pathogenic bacteria and fungi with MIC values ranging from 0.5-16.0 μg/mL. Compounds 7, 17, 20, and 22 demonstrated moderate activity against Micrococcus luteus with MIC values ranging from 35.6 to 71.1 μg/mL. Moreover, 1-3 displayed different degrees of antioxidant activity with EC₅₀ values of 0.98, 0.60, 0.46 mg/mL, respectively.